The invention relates to an apparatus for assembling on video tapes information retrieved from separate sound and/or image tracks.
For a long time, devices have been known which are combined under the common term image and sound editing tables and are provided to view one or more separate film tapes or to listen to one or more separate sound tapes and render it possible to associate or to combine these tapes in any desired manner. The processing on these known image and sound editing tables is usually preceded by the recording of the image with a camera and the simultaneous but separate recording of the corresponding sound with a conventional sound recording device. The image recorded by the film camera on a film image carrier and the sound recorded separately on a magnetic tape carrier were suitably synchronized one with the other on the image and sound editing table after the development of the film image carrier.
An especially important feature has to be met by these known editing devices in that a maximum synchronism has to be obtained between the film tape and the sound tape during the normal run with constant velocity as well as upon an accelerated run, so that the slip between the two tapes can be kept to a negligible minimum. For obtaining of the synchronism in all operational states, it has been proven especially advantageous that the transport perforation of the conventional film tape material could be used as a reference for determining the tape position relative to the other tape and depending therefrom controlling the tape drives such as to restore their synchronism, if necessary.
However, in addition to the recording technique with mechanical cameras using a conventional film tape, a different method for recording has emerged, namely the recording of images with the so-called video cameras. In a totally different way to the photographic film recording materials known so far, the images taken by a video camera are recorded on a magnetic tape which has a basic structure similar to that of the known magnetic tapes for the recording of sound. A distinguishing feature of the video tapes used for recording of images with video cameras resides in the fact that they are usually without any transport perforations, in contrast to conventional film tape material for use in mechanical cameras. If, for example, the recorded video tapes should be combined or assembled with other video tapes or with one or more other sound recordings made on conventional sound tapes, a highly accurate synchronism between the individual tapes in all operational states thereof constitutes an unalterable requirement for the practical usability of the device used as an image and sound editing table.
For guaranteeing an accurate synchronism between one or more video tapes as well as of one or more sound tapes and one or more separate image tapes, extremely expensive measures have hitherto been used. These known measures have been based on purely electronic systems operating with devices arranged at locations remote from the actual image and sound editing table. Furthermore, these known systems are extremely complicated to operate and may lead to considerable inaccuracies between the timing of individual tapes, namely the so-called static and/or dynamic dephasings. The operation of such complex image and sound editing tables provided with external electronic systems is considerably different from the working with conventional image and sound editing tables using classical working methods. Consequently, the operation can be performed with specially trained personnel only, under abandonment of the conventional working methods.